Modern internal combustion engines are equipped with sophisticated systems to monitor and control various aspects of engine performance during ongoing operation, to meet operator demands for performance, including torque and fuel economy, and to satisfy government regulations related to emissions, safety, and fuel economy. Such systems include sensing devices and actuators connected to one or more control modules which execute computer programs to monitor and control engine operation during ongoing operation.
Exhaust pressure is an important parameter used by engine system designers. For example, emissions requirements have led to implementation of exhaust gas recirculation (EGR) systems combined with aftertreatment systems to reduce engine emissions. Control of exhaust gas recirculation requires an accurate determination of EGR mass flow. Such methods include calculating EGR flow from a gas flow equation through an orifice, and, determining a difference between charge air mass flow and fresh air mass flow. Both calculations use engine exhaust pressure as one of the input variables.
Some engines are equipped with turbocharger devices, especially variable geometry turbochargers, to increase power output, achieve emissions targets, and improve fuel economy. Various government regulations require monitoring of vehicle and powertrain components which affect emissions, with requirements to timely detect and identify faults in the components.